Degradable packing element

ABSTRACT

A packing apparatus including at least one sealing surface formed from a degradable material. The degradable material may be a biodegradable polymer such as polyglocolic acid, polylactic acid, or their copolymers. The body of the packing apparatus may also be formed from a degradable material. The packing apparatus may be deployed in a subterranean well and disposed of without milling.

BACKGROUND

Packing elements are well known and often used components in downhole operations. Packing elements are annular structures used to press against an inside or outside diameter of a target tubular, typically sealing against the tubular, to prevent all fluid communication past the packing element/tubular interface. While the ubiquity of packing elements clearly evidences their effectiveness, these elements can interfere with subsequent operations, activities, production, etc., and physical removal of the packing elements, e.g., by fishing or intervention, can be difficult, costly, and time consuming. Therefore, the industry is receptive to advancements in packing element technology, particularly in designs that provide both a robust seal and the capability for selectively removing the packing element in order to facilitate subsequent operations.

SUMMARY

Disclosed herein is a packing apparatus for a well that includes a sealing element. The sealing element is formed from a degradable polymer and is configured to attach to a support structure.

Also disclosed herein is a packing apparatus including a body at least partially formed from a first degradable material. A first sealing surface, at least partially formed from a second degradable material, is disposed on the body.

Also disclosed herein is a well completion method using a packing apparatus of the present disclosure. The packing apparatus is arranged in a tubular and deployed at a selected location to restrict fluid flow. The well casing is then perforated above the selected location. A body of the packing apparatus is then degraded and a sealing surface of the packing apparatus is decomposed.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 is a cross-sectional view of a packing apparatus according to a first embodiment;

FIG. 2 is a cross-sectional view of a packing apparatus according to another embodiment;

FIG. 3 is a cross-sectional view of a plug assembly according to another embodiment; and

FIG. 4 is a cross-sectional view of a seat member of the plug assembly illustrated in FIG. 3.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. It is to be understood that other embodiments may be utilized and changes may be made without departing from the scope of the present disclosure. In particular, the disclosure provides various examples related to a packing apparatus for use in well operations, whereas the advantages of the present disclosure as applied in a related field would be apparent to one having ordinary skill in the art and are considered to be within the scope of the present invention.

FIG. 1 illustrates one embodiment of a packing apparatus 100 according to the present disclosure. The packing apparatus 100 comprises a body 105 and a sealing element 110. As illustrated, the sealing element 110 is attached to the body of the packing apparatus 100 to form a structure that when used to form a seal, can resist large fluid pressures.

In some embodiments, the sealing element 110 is at least partially formed from a degradable material. The degradable material may be a polymer, such as a degradable polymer or biodegradable polymer. As used herein, the term “biodegradable” is defined broadly to include materials that degrade in the presence of naturally occurring fluids, such as water, as well as enzymes and other biological compounds. While other elements of packing apparatuses, such as plugs, have been constructed of dissolvable or otherwise degradable materials, the creation of a sealing surface formed from a degradable material is counterintuitive to its purpose of providing a reliable seal. The packing apparatus disclosed herein is useful to reduce or eliminate milling after well completion and other downhole operations requiring a packing apparatus.

Generally, as used herein, the term “degradable” shall be used to mean able to corrode, dissolve, degrade, disperse, or otherwise be removed or eliminated, while “degrading” or “degrade” will likewise describe that the material is corroding, dissolving, dispersing, or otherwise being removed or eliminated. Any other form of “degrade” shall incorporate this meaning In some examples, the degradable material is configured to corrode, dissolve, disintegrate, decompose, degrade, or otherwise be removed based upon exposure to a fluid in contact therewith. The fluid may be a natural borehole fluid such as water, oil, etc. or may be a fluid added to the borehole for the specific purpose of degrading the material.

In some embodiments, and where as noted above, the degradable material element 110 is a degradable polymer, such as polyglycolic acid (PGA), polylactic acid (PLA), and their copolymers. These materials are known to decompose in water at elevated temperatures. Other examples of degradable polymers that are suitable for the sealing element 110 of the present disclosure include polycaprolactone (PCL), poly(hydroxyalkanoate)s, modified poly(saccharide)s, and other naturally occurring and synthetic polymers. These materials may be used in combination with each other and with other degradable and non-degradable polymers and other substances to achieve the desired mechanical properties, including degradation rate at a particular pressure and temperature.

The body 105 of the packing apparatus 100 comprises those elements that, when combined with the sealing element 110 and deployed, obstruct the flow of fluid in a tubular. In the embodiment illustrated in FIG. 2, the body 105 comprises a plug member 115, a seat member 120, a cone 125, and one or more slips 130. As disclosed herein, the body 105 may comprise a single element or an arrangement of numerous elements, as may be desired for a particular application.

In some embodiments, the body 105 of the packing apparatus 100 and the sealing element 110 are both formed, at least in part, from degradable materials. This allows the packing apparatus to be deployed in a subterranean well and disposed of without milling. The packing apparatus 100 of the present disclosure is disposable without sacrificing performance of the packing apparatus and the associated seal.

As mentioned above, the body 105 of the packing apparatus 100 is at least partially formed from a degradable material. In some embodiments, the degradable material chosen for the sealing element 110 may be the same degradable material selected for at least a portion of the body 105. In other embodiments, a first degradable material of the body 105 is selected to have a greater hardness than a second degradable material of the sealing element 110, thereby allowing the sealing element 110 to undergo some deformation to form the seal. The degradable material of the sealing element 110 may also be selected to have a slower rate of degradation than a degradable material selected to form at least a portion of the body 105. In theory, this would increase the likelihood that the seal remains intact at least until the body begins to be degraded. Further embodiments include a seal that comprises a degradable material that has a degradation rate that is greater than or equal to a degradation rate of the degradable material of the body 105.

In a further embodiment, the body 105 of the packing apparatus 100 is at least partially formed from a degradable material that may be activated, for example, by an acid or base solution. In some embodiments, the selected degradable material is adapted to degrade at a predictable rate when exposed to a selected fluid. In some examples, the degradable material is a controlled electrolytic metallic (CEM) material proprietary to Baker Hughes Incorporated. CEM materials generally comprise a nanomatrix metal composite containing a disintegrating agent. Some examples of these materials and their methods of manufacture are given in in U.S. Pat. No. 8,425,651, “Nanomatrix metal composite,” the entire contents of which are incorporated herein. These lightweight, high-strength and selectably and controllably degradable materials include fully-dense, sintered powder compacts formed from coated powder materials that include various lightweight particle cores and core materials having various single layer and multilayer nanoscale coatings. These powder compacts are made from coated metallic powders that include various electrochemically-active (e.g., having relatively higher standard oxidation potentials) lightweight, high-strength particle cores and core materials, such as electrochemically active metals, that are dispersed within a cellular nanomatrix formed from the various nanoscale metallic coating layers of metallic coating materials, and are particularly useful in borehole applications. Suitable core materials include electrochemically active metals having a standard oxidation potential greater than or equal to that of Zn, including as Mg, Al, Mn or Zn or alloys or combinations thereof. For example, tertiary Mg—Al—X alloys may include, by weight, up to about 85% Mg, up to about 15% Al and up to about 5% X, where X is another material. The core material may also include a rare earth element such as Sc, Y, La, Ce, Pr, Nd or Er, or a combination of rare earth elements. In other embodiments, the materials could include other metals having a standard oxidation potential less than that of Zn. Also, suitable non-metallic materials include ceramics, glasses (e.g., hollow glass microspheres), carbon, or a combination thereof. In one embodiment, the material has a substantially uniform average thickness between dispersed particles of about 50 nm to about 5000 nm. In one embodiment, the coating layers are formed from Al, Ni, W or Al2O3, or combinations thereof. In one embodiment, the coating is a multi-layer coating, for example, comprising a first Al layer, a Al2O3 layer, and a second Al layer. In some embodiments, the coating may have a thickness of about 25 nm to about 2500 nm.

Differences in the chemical compositions of coating material and core material may be selected to provide different dissolution rates and selectable and controllable dissolution of powder compacts that incorporate them making them selectably and controllably dissolvable. This includes dissolution rates that differ in response to a changed condition in the wellbore, including an indirect or direct change in a wellbore fluid. In one embodiment, a powder compact formed from powder having chemical compositions of core material and coating material that make compact is selectably dissolvable in a wellbore fluid in response to a changed wellbore condition that includes a change in temperature, change in pressure, change in flow rate, change in pH or change in chemical composition of the wellbore fluid, or a combination thereof. The selectable dissolution response to the changed condition may result from actual chemical reactions or processes that promote different rates of dissolution, but also encompass changes in the dissolution response that are associated with physical reactions or processes, such as changes in wellbore fluid pressure or flow rate.

In another embodiment, the degradable material is a metal composite that includes a metal matrix disposed in a cellular nanomatrix and a disintegration agent. The metal composite also includes the cellular nanomatrix that comprises a metallic nanomatrix material. The disintegration agent can be disposed in the cellular nanomatrix among the metallic nanomatrix material. Unlike elastomeric materials, the components of the degradable anchoring system herein that include the metal composite have a temperature rating up to about 1200° F., specifically up to about 1000° F., and more specifically about 800° F.

Referring again to FIG. 2, the sealing element 110 is arranged to form a seal with the inner surface of a tubular 135. In operation, the packing apparatus 100 is arranged in the tubular 135 at a selected location. The packing apparatus 100 may obstruct the fluid flow of fluid through the tubular 135 in order to actuate a valve, sleeve, or other device, in order to achieve the desired result. The sealing element 110 ensures that fluid pressure does not bypass the packing apparatus 100.

FIGS. 3 and 4 illustrate a plug assembly 200 in accordance with the present disclosure employing a sealing element in accordance with the present disclosure. The plug assembly 200 includes a first sealing element 205, disposed on an outer surface of a seat member 210. The first sealing element 205 is configured to form a sealing relationship with the inner surface of a tubular. In the illustrated embodiment, the plug assembly 200 also comprises a second sealing element 215 disposed on an inner surface of the seat member 210. The second sealing element 215 is configured to interface with a plug member to form a seal.

As discussed above, the body of the plug assembly 200 is at least partially formed from a degradable material. In some examples, the body may be formed entirely from a degradable material, such as the degradable materials discussed above. The body of the plug assembly 200 includes the seat member 210, a cone 220, and one or more slips 225, as well as a plug member (not shown).

The first sealing element 205 and the second sealing element 215 are formed from a material that includes a degradable polymer, such as polyglycolic acid. Other additives, which may include other degradable substances, may be added to the material of the first sealing element 205 and the second sealing element 215 to achieve the desired hardness and degradation rate. The first sealing element 205 and the second sealing element 215 can be formed using the same materials, or may be formed from different materials. The use of different materials in the sealing elements could be advantageous where the plug member and the tubular are formed from different substances.

In another embodiment, the present disclosure provides a method for well completion. A packing apparatus is arranged in a tubular, such as a casing or a piping string. The packing apparatus includes a body, formed at least partially from a degradable material, and at least one sealing element, formed at least partially from a degradable polymer. Alternatively, a plurality of packing apparatuses may be used at one or more stages. The packing apparatus is arranged in the tubular at a selected location and deployed to obstruct the flow of fluid. The casing is then perforated, for example, just above the selected location. The well may then be stimulated, for example, using proppant stimulation or another known process. When the last stage has been completed, the body of the packing apparatus is degraded, for example, by deploying a selected fluid that triggers a reaction in the degradable material. The sealing element is also degraded by fluid flow. For example, the degradable material may degrade into small particles in a matter of minutes while the degradable polymer will decompose over a number of days. The degradable materials discussed above are known to degrade in about 10 minutes or about 20 minutes in specific types of fluids, such as, for example, the selected fluid, depending on the size and composition of the object. By comparison, the degradable polymers discussed above may decompose over about 7 to 10 days, depending on bottom hole temperature. When the well completion method is accomplished according to the present disclosure, no milling of the tubular is required to begin or resume production.

The disclosure above describes exemplary embodiments of plug assemblies having ball seats. Other embodiments may include any number of ball seats having multiple seat portions, flow paths, alignment planes, and shapes of plug members that are operative to direct objects to engage the seats. Further, although the term “ball” is used herein to refer to the seats disclosed herein, it is to be understood that the seats may be used in connection with another type of plug or plug member, such as a plug dart. All such configurations are deemed to be within the scope of the present disclosure and are deemed to be encompassed by the term “plug member.”

While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. , do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. 

1. A packing apparatus for a well, comprising: a sealing element comprising a degradable polymer, the sealing element being configured to attach to a body.
 2. The packing apparatus of claim 1, the sealing element being configured to form a seal against an inner surface of a tubular.
 3. The packing apparatus of claim 1, the sealing element being configured to receive at least one plug member, the sealing element and the at least one plug member forming a seal.
 4. The packing apparatus of claim 4, the degradable polymer being at least partially formed from one or more of a polyglycolic acid, a polylactic acid, and combinations including at least one of the foregoing.
 5. The packing apparatus of claim 1, the body being at least partially formed from a degradable material.
 6. The packing apparatus of claim 6, the degradable material of the body being degradable when exposed to a selected fluid.
 7. The packing apparatus of claim 7, the degradable material being a controlled electrolytic metallic material.
 8. A packing apparatus, comprising: a body; and a first sealing element, the first sealing element being disposed on the body to interface with a tubular, the body and the first sealing element comprising a degradable material.
 9. The packing apparatus of claim 8, the body comprising a first degradable material and the first sealing element comprising a second degradable material.
 10. The packing apparatus of claim 8, the first sealing element configured to correspond with the inner surface of a tubular.
 11. The packing apparatus of claim 9, the body including a seat member and a plug member, a second sealing element being disposed on the seat member, the second sealing element and the plug member operatively forming a seal when the plug member is received by the second sealing element, the second sealing element being at least partially formed from the second degradable material.
 12. The packing apparatus of claim 9, the first degradable material being a controlled electrolytic metallic.
 13. The packing apparatus of claim 9, the second degradable material comprising a degradable polymer.
 14. The packing apparatus of claim 9, wherein a hardness of the first degradable material is greater than a hardness of the second degradable material.
 15. The packing apparatus of claim 9, wherein the first degradable material has a degradation rate that is greater than or equal to a degradation rate of the second degradable material.
 16. The packing apparatus of claim 9, wherein the second degradable material has a degradation rate that is greater than or equal to a degradation rate of the first degradable material.
 17. A well completion method, comprising: arranging at least one packing apparatus in a tubular; restricting fluid flow through the tubular by deploying the at least one packing apparatus at a selected location; degrading one or more of a body of the at least one packing apparatus and a sealing element of the at least one packing apparatus.
 18. The method of claim 17, wherein degrading the body of the at least one packing apparatus comprises delivering a selected fluid that causes the body of the packing apparatus to degrade.
 19. The method of claim 17, wherein the sealing element comprises a degradable polymer. 